Wow, 50 cents sounds like a lot. I'd like to see their math. Of course, it would depend enormously on what kind of mid-sized car you drive - a Kia, a Toyota, or a BMW.
But let's say you spent $25,000 on your car and you drive it 20,000 miles per year for 4 years. At 50 cents a mile, you would have gotten back $40,000. Let's say you then sell the car for $9000. So you've spent $25,000 and got back $49,000. That's a $24,000 difference. I don't think four years of gas, maintenance, and insurance for a new car could come out to $24,000.
I think the 50 cents a mile figure might be appropriate for higher end cars but not for low to mid-priced cars.
Beakybird